Local sharing saves network bandwidth

By Comms sector newsdesk

Published Wednesday, August 20, 2008

Bandwidth problems caused by Internet file sharing could be eased if peer to peer software tried to be more neighbourly, according to researchers at the University of Washington and Yale University who have developed an algorithm that attempts to do just that.

File sharing is estimated to produce 50% to 80% of internet traffic .Internet service providers (ISPs) have challenged organisations such as the BBC, which uses peer to peer software in its iPlayer media-on-demand service, to contribute to the costs of upgrading their networks to cope with the load.

The Washington and Yale researchers will present a paper on the new algorithm, known as P4P, at this week's Association for Computing Machinery's Special Interest Group on Data Communications meeting in Seattle.

"Initial tests have shown that network load could be reduced by a factor of five or more without compromising network performance," said co-author Arvind Krishnamurthy, a University of Washington research assistant professor of computer science and engineering. "At the same time, speeds are increased by about 20 percent."

The problem with current peer to peer protocols is that they have no sense of where data is located. So a file is as likely to be downloaded from another country as it is from next door. This loads the internet's major international connections with unnecessary traffic.

"We realised that P2P networks were not taking advantage of the flexibility that exists," said the paper's co-author Richard Yang, an associate professor of computer science at Yale.

In their tests, the researchers calculated that the average peer-to-peer data packet travels 1000 miles and takes 5.5 metro hops (connections through major hubs). With the new system, data travelled an average of 160 miles across an average of just 0.89 metro hops, dramatically reducing Web traffic on major links between cities.

The tests also showed that only 6 percent of file sharing is done locally. With the new algorithms, local file sharing increased to 58 percent.

The P4P system relies on ISPs providing a number that acts as a weighting factor for network routing, so it is necessary for the ISP to co-operate with the file-sharing host. But the system does not force companies to disclose proprietary information about how they route Internet traffic.